1. Field of the Invention
The invention relates to a magnetic resonance (MR) spectroscopy method in which an examination Zone is exposed, preferably repeatedly, to a sequence which comprises a first frequency-selective 90.degree. RF pulse for water suppression, followed by a 180.degree. RF pulse, and also relates to a device for performing this method.
2. Description of the Prior Art
A method of this kind is known from "Book of Abstracts" of S.M.R.M., Vol. 3, 1986, pp. 981 and 982. Therein, the frequency-selective 90.degree. RF pulse in the form of a binomial pulse leaves the water-bound protons substantially unexcited but excites the protons bound to lactic acid. The presence of lactic acid in biological tissues thus can be demonstrated, even though the water signal is from three to four powers of ten larger than the signal produced by lactic acid if the 90.degree. RF pulse is not a binomial pulse.
The 180.degree. RF pulse succeeding the first binomial 90.degree. RF Pulse serves to select a voxel, in cooperation with two further 180.degree. RF pulses (each time in conjunction with a magnetic gradient field), and to determine the lactic acid contents in this voxel in conjunction with the binomial RF pulse.
The known method has been tested on a lactic acid phantom. In clinical practice, however, it is substantially more difficult to demonstrate the Presence of lactic acid, because in the frequency range in which the lactic acid signals occur a signal is also generated by lipids.
3. Object of the Invention
It is the object of the invention to provide a method of the kind set forth so that the presence of either lactic acids oz lipids can be separately demonstrated in the presence of water.